>Does it have to be a scan? Maybe it can be done with an SQL command? ::: yes I gess it has to be a scan because inside it I do call other functions...
>
>Are you sure that SCAN itself is responsible for slowdown not what you're doing inside the scan? :::: yes, Is the scan because I've commented (**-) all code inside and is the same
>
>Are you setting order in the table before scan? :::: I try it now (set order to tag cType) without better resoults...

Setting index will slow down a scan. You should follow Cetin's suggestion but peek the index that returns least number of records. Another option is to create a combine index on 2 fields.